反应详情

To a solution of 4-isobutyl-5-methyl-thiophene-2-carboxylic acid (126 mg, 637 μmol) in DCM (5 mL), DIPEA (249 mg, 1.93 mmol) is added followed TBTU (202 mg, 628 μmol). The mixture is stirred at rt for 30 min before 3-[2-ethyl-4-(N-hydroxycarbamimidoyl)-6-methyl-phenyl]-propionic acid (159 mg, 637 μmol) is added. The mixture is stirred at rt for 16 h before it is diluted with DCM, washed with 1 N aq. HCl solution, dried over Na2SO4, filtered and concentrated. The residue is dissolved in toluene (20 mL) and the reaction mixture is stirred at 110° C. for 18 h. The solvent is evaporated and the crude product is purified by CC on silica gel eluting with DCM containing 5% of methanol to give 3-{2-ethyl-4-[5-(4-isobutyl-5-methyl-thiophen-2-yl)-[1,2,4]oxadiazol-3-yl]-6-methyl-phenyl}-propionic acid (41 mg) as a beige solid; LC-MS: tR=1.17 min, [M+1]+=413.30; 1H NMR (CDCl3): δ 0.94 (d, J=6.4 Hz, 6H), 1.30 (t, J=7.6 Hz, 3H), 1.84-1.96 (m, 1H), 2.43 (s, 3H), 2.45 (s, 3H), 2.46-2.60 (m, 4H), 2.75 (q, J=7.3 Hz, 2H), 3.02-3.12 (m, 2H), 7.66 (s, 1H), 7.79 (s, 1H), 7.81 (s, 1H).

1. additionis added
2. washwashed with 1 N aq. HCl solution
3. dry with materialdried over Na2SO4
4. filtrationfiltered
5. concentrationconcentrated
6. dissolutionThe residue is dissolved in toluene (20 mL)
7. stirringthe reaction mixture is stirred at 110° C. for 18 h
8. customThe solvent is evaporated
9. customthe crude product is purified by CC on silica gel eluting with DCM containing 5% of methanol